High-temperature oxidation-resistant carbon-graphite material for aero-engines and method for producing same

Abstract

The application discloses an aero-engine high-temperature antioxidant carbon graphite material and a preparation method thereof, and belongs to the technical field of carbon graphite materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon graphite materials, and particularly relates to a high-temperature oxidation-resistant carbon graphite material for an aero-engine and a preparation method thereof. BACKGROUND

[0002] Carbon graphite materials are widely used in the sealing system of an aero-engine due to their good electrical conductivity and thermal conductivity, excellent self-lubricity, low thermal expansion coefficient, stable chemical properties, high wear resistance and the like, and can meet the requirements of high performance, high reliability and high stability in the field of aerospace.

[0003] However, with the rapid development of special fields such as aerospace, the sealing system components need to withstand higher end face pressure and faster rotating speed, and work in a severe oscillating oxidation atmosphere, which requires the carbon graphite sealing material to have certain high-temperature oxidation resistance and be able to withstand greater impact force to meet the upgrading and replacement requirements of aero-engines and gas turbines and other cutting-edge equipment.

[0004] In view of the problem that carbon graphite materials are easily oxidized in a high-temperature environment, domestic and foreign scholars have carried out a large amount of research work. The improvement methods mainly include matrix modification, surface coating and solution impregnation, specifically:

[0005] The general matrix modification method is to add ceramic powder and other oxidation inhibitors in the carbon graphite matrix to improve the oxidation resistance of the material. However, the ceramic powder has poor compatibility with carbon aggregates and binders, resulting in relatively poor homogeneity, stability and service life of the carbon graphite sealing product.

[0006] The surface coating method is to prepare an oxidation-resistant coating on the surface of the part by physical or chemical vapor deposition, spraying and the like. However, the thermal expansion coefficients of the matrix material and the coating material do not match, resulting in cracks between the coating and the base material and damage, poor resistance to mechanical impact and thermal impact of the oxidation-resistant coating, easy peeling off from the surface, causing abrasive wear and reducing the oxidation resistance of the graphite material.

[0007] The solution impregnation method improves the mechanical properties and oxidation resistance of the product by impregnation, but the current impregnant is prone to deliquescence, which weakens the oxidation resistance.

[0008] Therefore, it is urgent to improve the high-temperature oxidation resistance of carbon graphite materials on the basis of meeting the basic mechanical property requirements, so as to meet the upgrading and replacement requirements of aero-engines and gas turbines and other cutting-edge equipment in China. SUMMARY

[0009] In view of the above-mentioned deficiencies existing in the prior art, the purpose of the present application is to provide a high-temperature oxidation-resistant carbon graphite material for an aero-engine and a preparation method thereof.

[0010] The technical scheme of the present application is implemented as follows:

[0011] A preparation method of a high-temperature oxidation-resistant carbon graphite material for an aero-engine, specifically comprising the following steps:

[0012] (1) coke powder with D50 less than 10 μm is put into a mixing kettle for mixing, after removing water, the temperature is raised to 160-190 ℃, then pitch A in a molten state is put into the mixing kettle for mixing, after cooling, the mixture is broken, sieved and molded, then semi-coking treatment is carried out, and then the mixture is broken and sieved to obtain modified powder A; wherein the mass ratio of the coke powder and the pitch A is 6-7:3-4;

[0013] (2) graphite waste powder with D50 less than 10 μm is put into a mixing kettle for mixing, after removing water, the temperature is raised to 160-190 ℃, then pitch B in a molten state is put into the mixing kettle for mixing, after cooling, the mixture is broken, sieved and molded, then semi-coking treatment is carried out, and then the mixture is broken and sieved to obtain modified powder B; wherein the mass ratio of the graphite waste powder and the pitch B is 6-7:3-4;

[0014] (3) an oxidation inhibitor is put into a mixing kettle for mixing, after removing water, the temperature is raised to 160-190 ℃, then pitch C in a molten state is put into the mixing kettle for mixing, after cooling, the mixture is broken, sieved and molded, then semi-coking treatment is carried out, and then the mixture is broken and sieved to obtain modified powder C; wherein the mass ratio of the oxidation inhibitor and the pitch C is 6-7:3-4;

[0015] (4) the modified powder A, the modified powder B and the modified powder C are mixed in a proportion of 35-40:60-65:5-20 in a mixing machine, after removing water, the temperature is raised to 180-210 ℃, then pitch D in a molten state is put into the mixing kettle for mixing, and then the mixture is rolled, broken, sieved to obtain a pressed powder; the mass ratio of the mixed powder and the pitch D is 105-115:40-43;

[0016] It is found through research that, with the increase of the modified powder C, the comprehensive mechanical properties and the oxidation resistance of the carbon graphite material will first increase and then decrease, and when the amount of the oxidation inhibitor is too much, the comprehensive mechanical properties and the oxidation resistance of the carbon graphite block material will sharply decrease, which cannot meet the requirements of practical application, and the reason is that when the amount of the oxidation inhibitor is too much, the phase interface in the composite system increases, and the active sites for the reaction of carbon atoms increase, which makes the oxidation resistance decrease. The mass ratio of the modified powder A, the modified powder B and the modified powder C is preferably 35-40:60-65:10-18.

[0017] (5) The green body block obtained in step (4) is formed by powder pressing molding, and then is placed in a graphite crucible to be baked to obtain a baked block with a density of 1.70-1.76 g / cm 3 .

[0018] (6) The baked block obtained in step (5) is treated in a graphitization furnace at 2500-2800 ℃ for 2-6 h, and then is cooled to 200-300 ℃ in a programmed manner and is naturally cooled to room temperature to obtain a carbon graphite material with a density of 1.80-1.87 g / cm 3 .

[0019] Further, the coke powder is obtained by coke pretreatment, and the coke is one or more of calcined pitch coke, needle coke and Shenmu coke.

[0020] Further, in step (2), the magnetic impurities in the graphite waste powder are removed by using a special magnetic separation device, and then the graphite waste powder is coarsely ground by using a Raymond mill and finely ground by using a super-micro grinding mill.

[0021] Further, the oxidation inhibitor is one or more of boron nitride, boron carbide and zirconium diboride.

[0022] Further, the pitch A in step (1), the pitch B in step (2), the pitch C in step (3) and the pitch D in step (4) are one or two of impregnated pitch, medium-temperature pitch, high-temperature pitch and modified pitch.

[0023] Further, in step (4), the mixing feeding is mixed in a 100-110 ℃ environment for 30-60 min, and then the temperature is increased to 180-210 ℃ after the water is removed, the molten pitch D is added to the mixing pot, the rotating speed of the mixing pot is 30-50 r / min, and the mixing pot is closed for 0.5-1.5 h.

[0024] Further, in step (4), the mixed paste after mixing is quickly put into a sheeting machine, the sheeting is performed for 1-3 times, the sheeting thickness is 1-2.5 mm, the sheeting temperature is 180-200 ℃, the material is cooled according to the program after the sheeting is completed, the material is placed for 5 h, and then is broken, ground, and sieved through a 100-400 mesh screen, and then is placed for 5-10 h, so as to obtain the powder.

[0025] Further, the semi-coke treatment in steps (1), (2) and (3) is specifically as follows: the powder obtained in steps (1), (2) and (3) is formed by molding under a pressure of 5-20 MPa, is placed in a box-type resistance furnace, the air in the furnace is replaced by nitrogen, the temperature increasing rate is 20 ℃ / h, the final temperature in the furnace is controlled to be 400-600 ℃, the final temperature is kept for 3-6 h, and then the material is broken and sieved after being cooled with the furnace, and finally the modified powder is obtained.

[0026] Further, the specific step of step (5) is: powdering under 1-3 MPa mold pressing forming, packaging in a vacuum packaging bag, placing for 2-4 h, and then cold isostatic pressing under a pressure of 140-200 MPa, gradient pressure relief; after taking out and placing for 4-6 h, a green body block with a density of 1.58-1.63 g / cm 3 3 is obtained; then the green body block is placed in a graphite crucible, filled with sand, the crucible is placed in a calcination furnace, argon is introduced, the temperature is raised according to the program, and the calcination is carried out at 900-1200 ℃ for 2-4 h, and then the temperature is lowered to 200-400 ℃ according to the program and naturally cooled, so that the calcined block with a density of 1.70-1.76 g / cm 3 is obtained.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] 1、The present application forms a carbonized layer and a carbide with activity on the surface and pores of the coke powder, graphite waste powder and oxidation inhibitor by preparing modified powder A, modified powder B and modified powder C from the coke powder, graphite waste powder and oxidation inhibitor respectively, thereby effectively reducing the difference in thermal expansion coefficient between the graphite powder, coke powder and oxidation inhibitor, promoting the interface bonding of the aggregate and the oxidation inhibitor, avoiding the cracking of the green body block prepared in the heat treatment process, ensuring the mechanical properties of the carbon graphite material, and improving the oxidation resistance of the carbon graphite material.

[0029] 2、The carbon graphite material prepared in the present application can form a glassy substance by reacting with oxygen before the matrix material, and can construct an oxidation-resistant protective film on the surface of the carbon aggregate. At the same time, the modification of the oxidation inhibitor can effectively disperse the agglomerates and uniformly distribute them in the carbon matrix, and the constructed surface interface active layer has good bonding with the functional groups on the surface of the aggregate, which is beneficial to improve the mechanical properties and oxidation resistance of the carbon graphite material.

[0030] 3、The present application uses low-cost graphite waste powder as one of the aggregates to prepare the carbon graphite material, which reduces the raw material cost of preparing the carbon graphite material, improves the added value and usage of the graphite waste powder, and the graphite waste powder has high graphitization degree and good oxidation resistance, so that it is beneficial to improve the oxidation resistance of the carbon graphite material when used as an aggregate.

[0031] 4、The carbon graphite sealing material prepared in the present application has a compact one-time structure, good homogeneity and excellent comprehensive performance. The preparation method of the present application greatly shortens the production cycle, saves the labor cost and equipment investment cost, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1- Flexural and compressive strength diagrams of the carbon graphite material prepared in Example 1 and corresponding fracture micrographs.

[0033] Figure 2 - Flexural and compressive strength diagrams of the carbon graphite material prepared in Example 2 and corresponding fracture micrographs.

[0034] Figure 3 - Flexural and compressive strength diagrams of the carbon graphite material prepared in Example 3 and corresponding fracture micrographs.

[0035] Figure 4 - Flexural and compressive strength diagrams of the carbon graphite material prepared in Comparative Example 1 and corresponding fracture micrographs. DETAILED DESCRIPTION

[0036] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] 1) The coke powder and graphite waste powder purchased were broken into fine powder with D50≤10 μm using a super micro pulverizer, and were used as needed;

[0039] 2) 64 parts of coke powder and 36 parts of pitch (20 parts of impregnated pitch and 16 parts of modified pitch) were taken, the coke powder was put into a kneading pot, and was kneaded at 110 °C for 1 h at a rotation speed of 15 r / min to remove water, and then the temperature of the kneading pot was raised to 180 °C, and the pitch in a molten state was put in, and was kneaded for 1 h with the cover closed at a rotation speed of 50 r / min. After the kneading was completed, the paste was poured out to cool the material, was broken, and was passed through a 160 mesh sieve to obtain a pressed powder. After being left for 5 h, the pressed powder was molded at 10 MPa, was broken after semi-coke treatment, and was sieved to obtain modified powder A;

[0040] 3) 67 parts of graphite waste powder and 33 parts of pitch (13 parts of impregnated pitch and 20 parts of modified pitch) were taken, the graphite waste powder was put into a kneading pot, and was kneaded at 110 °C for 1 h at a rotation speed of 15 r / min to remove water, and then the temperature of the kneading pot was raised to 180 °C, and the pitch in a molten state was put in, and was kneaded for 1 h with the cover closed at a rotation speed of 50 r / min. After the kneading was completed, the paste was poured out to cool the material, was broken, and was passed through a 160 mesh sieve to obtain a pressed powder. After being left for 5 h, the pressed powder was molded at 10 MPa, was broken after semi-coke treatment, and was sieved to obtain modified powder B;

[0041] 4) Take oxidation inhibitor 65 parts (boron nitride 35 parts, zirconium diboride 20 parts, boron carbide 10 parts), pitch 35 parts (including impregnated pitch 15 parts, medium temperature pitch 20 parts), put the oxidation inhibitor into the mixing kettle, mix at 110 ℃ for 1 h, the speed is 15 r / min, remove the water, then increase the temperature of the mixing kettle to 180 ℃, put in the molten pitch, close the cover and mix for 1 h, the speed is adjusted to 50 r / min. After mixing, pour out the paste, cool the material, crush and pass through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, crushed and sieved after semi-coking treatment to obtain modified powder C;

[0042] 5) Accurately weigh high temperature pitch 40 parts, take modified powder A 40 parts, modified powder B 60 parts, and modified powder C 5 parts;

[0043] 6) Mix the modified powder A, modified powder B and modified powder C in a mixing machine for 30 min, then put them into the mixing kettle, remove the water at 110 ℃, the speed is 15 r / min, then increase the temperature in the kettle to 200 ℃, put in the high temperature pitch at the corresponding temperature, adjust the speed to 50 r / min, close the cover and mix for 1 h.

[0044] 7) Quickly put the paste obtained in 6) into a tablet press, the tablet press temperature is 200 ℃, roll the tablet 3 times, the tablet thickness is 2 mm, after tabletting, cool the material, stand for 5 h, then crush and pass through a 200 mesh sieve; stand for 5 h to obtain a pressed powder;

[0045] 8) The pressed powder obtained in 7) is molded at 1 MPa, packaged in a vacuum packaging bag, and after standing for 2 h, cold isostatic pressing is carried out at 140 MPa for 30 min, and gradient pressure relief is carried out; after standing for 5 h, a green body block with a density of 1.60 g / cm 3 is obtained;

[0046] 9) The green body block obtained in 8) is placed in a graphite crucible, filled with sand, and placed in a calcination furnace, argon is introduced, and the temperature is increased according to the program, calcined at 1000 ℃ for 4 h, and then cooled to 200 ℃ by program control, and naturally cooled to room temperature, to obtain a calcined block with a density of 1.76 g / cm 3 .

[0047] 10) The calcined block is treated in a graphitization furnace at 2500 ℃ for 4 h, then cooled to 200 ℃ by program control, and naturally cooled to room temperature, to obtain a graphitized block with a density of 1.85 g / cm 3 .

[0048] The bending strength and compressive strength of the carbon graphite material obtained in this example and the corresponding cross-sectional microstructure diagram are shown in Figure 1 , Figure 1 (a) andFigure 1 (b) are respectively the bending strength and compressive strength diagrams of the carbon graphite material, Figure 1 (c) and Figure 1 (d) are respectively the cross-section micro-morphology diagrams of the carbon graphite material. From Figure 1 (a) and 1 (b), the bending strength and compressive strength of the carbon graphite material are respectively 62.78 MPa and 117.70 MPa. From Figure 1 (c) and Figure 1 (d), it can be seen that the obvious size particles are tightly combined, the holes are few, and the pore size is small, and no cracks appear, so the carbon graphite material prepared exhibits excellent bending and compressive strength.

[0049] Example 2

[0050] 1) The purchased coke powder and graphite waste powder were crushed into fine powder with D50≤10 μm by using a super micro pulverizer, and were used as needed;

[0051] 2) Take 64 parts of coke powder and 36 parts of pitch (including 20 parts of impregnated pitch and 16 parts of modified pitch), put the coke powder into the mixing pot, knead at 110 ℃ for 1 h, the rotating speed is 15 r / min, remove the water, then raise the temperature of the mixing pot to 180 ℃, put in the molten pitch, close the cover and knead for 1 h, the rotating speed is adjusted to 50 r / min. After kneading, the paste is poured out and cooled, crushed, and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, and after semi-coking treatment, it is crushed and sieved to obtain modified powder A;

[0052] 3) Take 67 parts of graphite waste powder and 33 parts of pitch (including 13 parts of impregnated pitch and 20 parts of modified pitch), put the graphite waste powder into the mixing pot, knead at 110 ℃ for 1 h, the rotating speed is 15 r / min, remove the water, then raise the temperature of the mixing pot to 180 ℃, put in the molten pitch, close the cover and knead for 1 h, the rotating speed is adjusted to 50 r / min. After kneading, the paste is poured out and cooled, crushed, and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, and after semi-coking treatment, it is crushed and sieved to obtain modified powder B;

[0053] 4) Take oxidation inhibitor 65 parts (including boron nitride 30 parts, zirconium diboride 25 parts, boron carbide 10 parts), pitch 35 parts (including impregnated pitch 15 parts, medium temperature pitch 20 parts), put the oxidation inhibitor into the mixing kettle, mix at 110 ℃ for 1 h, the speed is 15 r / min, remove the water, then increase the temperature of the mixing kettle to 180 ℃, put in the molten pitch, close the cover and mix for 1 h, the speed is adjusted to 50 r / min. After mixing, pour out the paste, cool the material, crush, and pass through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, crushed and sieved after semi-coking treatment to obtain modified powder C;

[0054] 5) Accurately weigh high temperature pitch 43 parts, take modified powder A 40 parts, modified powder B 60 parts, and modified powder C 10 parts;

[0055] 6) Mix the modified powder A, modified powder B and modified powder C in a mixing machine for 30 min, then put them into the mixing kettle, remove the water at 110 ℃, the speed is 15 r / min, then increase the temperature in the kettle to 200 ℃, put in the high temperature pitch at the corresponding temperature, adjust the speed to 50 r / min, close the cover and mix for 1 h.

[0056] 7) Quickly put the paste obtained in 6) into a tablet press, the tablet press temperature is 200 ℃, roll the tablet 3 times, the tablet thickness is 2 mm, after tabletting, cool the material, stand for 5 h, then crush and pass through a 200 mesh sieve; stand for 5 h to obtain a pressed powder;

[0057] 8) The pressed powder obtained in 7) is molded at 1 MPa, packaged in a vacuum packaging bag, and after standing for 2 h, cold isostatic pressing is carried out at 140 MPa for 30 min, and gradient pressure relief is carried out; after standing for 5 h, a green body block with a density of 1.61 g / cm 3 is obtained;

[0058] 9) The green body block obtained in 8) is placed in a graphite crucible, filled with sand, and placed in a calcination furnace, argon is introduced, and the temperature is increased according to the program, calcined at 1000 ℃ for 4 h, and then cooled to 200 ℃ by program control, and naturally cooled to room temperature, to obtain a calcined block with a density of 1.75 g / cm 3 .

[0059] 10) The calcined block obtained in 9) is treated at 2500 ℃ for 4 h in a graphitization furnace, then cooled to 200 ℃ by program control, and naturally cooled to room temperature, to obtain a graphitized block with a density of 1.87 g / cm 3 .

[0060] The bending strength and compressive strength of the carbon graphite material obtained in this example and the corresponding cross-sectional microstructure diagram are shown in Figure 2 , Figure 2(a) and Figure 2 (b) are the flexural strength and compressive strength diagrams of the carbon graphite material, respectively, Figure 2 (c) and Figure 2 (d) are the cross-section micro-morphology diagrams of the carbon graphite material, respectively. Figure 2 From (a) and (b), the flexural strength and compressive strength of the carbon graphite material are 65.83 MPa and 120.38 MPa, respectively. Figure 2 (c) and Figure 2 (d) can be obviously combined with the size of the particles, and the pores are less and the pore size is smaller, and no cracks appear, so the carbon graphite material prepared exhibits excellent flexural and compressive strength.

[0061] Example 3

[0062] 1) The purchased coke powder and graphite waste powder were crushed into fine powder with D50≤10 μm by using a super micro pulverizer, and were used as needed.

[0063] 2) Take 64 parts of coke powder and 36 parts of pitch (including 20 parts of impregnated pitch and 16 parts of modified pitch), put the coke powder into the mixing pot, mix at 110 ℃ for 1 h, the speed is 15 r / min, remove the water, then raise the temperature of the mixing pot to 180 ℃, put in the molten pitch, close the cover and mix for 1 h, the speed is adjusted to 50 r / min. After mixing, the paste is poured out and cooled, crushed and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, and after semi-coking treatment, it is crushed and sieved to obtain modified powder A;

[0064] 3) Take 67 parts of graphite waste powder and 33 parts of pitch (including 13 parts of impregnated pitch and 20 parts of modified pitch), put the graphite waste powder into the mixing pot, mix at 110 ℃ for 1 h, the speed is 15 r / min, remove the water, then raise the temperature of the mixing pot to 180 ℃, put in the molten pitch, close the cover and mix for 1 h, the speed is adjusted to 50 r / min. After mixing, the paste is poured out and cooled, crushed and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, and after semi-coking treatment, it is crushed and sieved to obtain modified powder B;

[0065] 4) Take oxidation inhibitor 65 parts (including boron nitride 25 parts, zirconium diboride 25 parts, boron carbide 15 parts), pitch 35 parts (including impregnated pitch 15 parts, medium temperature pitch 20 parts), put the oxidation inhibitor into the mixing kettle, mix at 110 ℃ for 1 h, the speed is 15 r / min, remove the water, then increase the temperature of the mixing kettle to 180 ℃, put in the molten pitch, close the cover and mix for 1 h, the speed is adjusted to 50 r / min. After mixing, pour out the paste, cool the material, crush, and pass through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder is molded at 10 MPa, crushed and sieved after semi-coking treatment to obtain modified powder C;

[0066] 5) Accurately weigh high temperature pitch 40 parts, take modified powder A 40 parts, modified powder B 60 parts, and modified powder C 15 parts;

[0067] 6) Mix the modified powder A, modified powder B and modified powder C in a mixing machine for 30 min, then put them into the mixing kettle, remove the water at 110 ℃, the speed is 15 r / min, then increase the temperature in the kettle to 200 ℃, put in the high temperature pitch at the corresponding temperature, adjust the speed to 50 r / min, close the cover and mix for 1 h.

[0068] 7) Quickly put the paste obtained in 6) into a tablet press, the tablet press temperature is 200 ℃, roll the tablet 3 times, the tablet thickness is 2 mm, after rolling the tablet, cool the material, and stand for 5 h, then crush and pass through a 200 mesh sieve; stand for 5 h to obtain a pressed powder;

[0069] 8) The pressed powder obtained in 7) is molded at 1 MPa, packaged in a vacuum packaging bag, and after standing for 2 h, cold isostatic pressing is carried out at 140 MPa for 30 min, and gradient pressure relief is carried out; after standing for 5 h, a green body block with a density of 1.60 g / cm 3 is obtained;

[0070] 9) The green body block obtained in 8) is placed in a graphite crucible, filled with sand, and placed in a calcination furnace, argon is introduced, and the temperature is increased according to the program, calcined at 1000 ℃ for 4 h, and then cooled to 200 ℃ by program, and naturally cooled to room temperature, to obtain a calcined block with a density of 1.76 g / cm 3 .

[0071] 10) The calcined block obtained in 9) is treated at 2500 ℃ for 4 h in a graphitization furnace, and then cooled to 200 ℃ by program, and naturally cooled to room temperature, to obtain a graphitized block with a density of 1.86 g / cm 3 .

[0072] The bending strength and compressive strength of the carbon graphite material obtained in this example and the corresponding cross-sectional microstructure diagram are shown in Figure 4 , and Figure 3(a) and Figure 3 (b) are the flexural strength and compressive strength diagrams of the carbon graphite material, respectively, Figure 3 (c) and Figure 3 (d) are the cross-section micro-morphology diagrams of the carbon graphite material, respectively. Figure 3 As can be seen from (a) and (b), the flexural strength and compressive strength of the carbon graphite material are 69.36 MPa and 139.83 MPa, respectively. As can be seen from (c) and (d), Figure 3 (c) and Figure 3 (d), the size of the particles is obviously close, the holes are few, and the pore size is small, and no cracks appear, so the carbon graphite material prepared exhibits excellent flexural and compressive strength.

[0073] Comparative Example 1

[0074] 1) The coke powder and graphite waste powder purchased were crushed into fine powder with D50≤10 μm by using a super micro pulverizer, and were used as needed.

[0075] 2) 64 parts of coke powder and 36 parts of pitch (including 20 parts of impregnated pitch and 16 parts of modified pitch) were taken, the coke powder was put into a kneading pot, kneaded at 110 ℃ for 1 h, the rotating speed was 15 r / min, and the water was removed, then the temperature of the kneading pot was increased to 180 ℃, the pitch in molten state was put in, and the kneading was closed for 1 h, the rotating speed was adjusted to 50 r / min. After the kneading was finished, the paste was poured out to cool the material, crushed, and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder was molded at 10 MPa, and after the semi-coking treatment, it was crushed and sieved to obtain modified powder A.

[0076] 3) 67 parts of graphite waste powder and 33 parts of pitch (including 13 parts of impregnated pitch and 20 parts of modified pitch) were taken, the graphite waste powder was put into a kneading pot, kneaded at 110 ℃ for 1 h, the rotating speed was 15 r / min, and the water was removed, then the temperature of the kneading pot was increased to 180 ℃, the pitch in molten state was put in, and the kneading was closed for 1 h, the rotating speed was adjusted to 50 r / min. After the kneading was finished, the paste was poured out to cool the material, crushed, and sieved through a 160 mesh sieve to obtain a pressed powder. After 5 h, the pressed powder was molded at 10 MPa, and after the semi-coking treatment, it was crushed and sieved to obtain modified powder B.

[0077] 4) Accurately weigh 40 parts of high temperature pitch, take 40 parts of modified powder A, and 60 parts of modified powder B;

[0078] 5) The modified powder A and the modified powder B were mixed in a mixing machine for 30 min, then put into a kneading pot, removed the water at 110 ℃, the rotating speed was 15 r / min, then the temperature in the pot was increased to 200 ℃, the corresponding temperature of the high temperature pitch was put in, the rotating speed was adjusted to 50 r / min, and the kneading was closed for 1 h.

[0079] 6) The paste obtained in 5) is quickly put into a tablet press, the tablet press temperature is 200 ℃, tablet pressing is performed 3 times, the tablet thickness is 2 mm, after tablet pressing, the material is cooled, and is placed for 5 h, and then is broken, and is passed through a 200 mesh screen; after standing for 5 h, a pressed powder is obtained;

[0080] 7) The pressed powder obtained in 6) is molded by die pressing at 1 MPa, is packaged in a vacuum packaging bag, is placed for 2 h, and then is cold isostatic pressed at a pressure of 140 MPa for 30 min, and is gradiently released; after being taken out and placed for 5 h, a green body with a density of 1.62 g / cm 3 is obtained;

[0081] 8) The green body obtained in 7) is placed in a graphite crucible, is filled with sand, and is placed in a calcination furnace, argon is introduced, and temperature is raised according to a program, is calcined at 1000 ℃ for 4 h, is cooled to 200 ℃ according to a program, and is naturally cooled, and a calcined body with a density of 1.70 g / cm 3 is obtained.

[0082] 9) The calcined body obtained in 8) is treated in a graphitization furnace at 2500 ℃ for 4 h, is controlled to be cooled to 200 ℃ according to a program, and is naturally cooled to room temperature, and a graphitized body with a density of 1.81 g / cm 3 is obtained.

[0083] The bending strength and compressive strength diagrams and the corresponding cross-sectional micro-morphology diagrams of the carbon graphite material obtained in the example are as shown in Figure 4 , Figure 4 (a) and Figure 4 (b) are respectively the bending strength and compressive strength diagrams of the carbon graphite material, Figure 4 (c) and Figure 4 (d) are respectively the cross-sectional micro-morphology diagrams of the carbon graphite material. As can be seen from (a) and (b), the bending strength and compressive strength of the carbon graphite material are respectively 59.35 MPa and 101.17 MPa. As can be seen from (c) and (d), the pore size between the particles is large, and the pore distribution is obvious, so the comprehensive performance of the prepared carbon graphite material is inferior to that of Examples 1 to 3. Figure 4 Figure 4 Figure 4

[0084] Comparative Example 2

[0085] 1) A purchased coke powder and graphite waste powder are broken into fine powder with D50≤10 μm by using a super micro grinder, and are used;

[0086] ​​​2) Take 64 parts of coke powder, 36 parts of pitch (including 20 parts of impregnated pitch and 16 parts of modified pitch), put the coke powder into the mixing kettle, knead at 110°C for 1h, the speed is 15r / min, remove the water, then raise the temperature of the mixing kettle to 180°C, put in the molten pitch, close the cover and knead for 1h, the speed is adjusted to 50r / min. After kneading, pour out the paste, cool the material, crush and pass through a 160 mesh sieve to get the pressed powder. After 5h, press the pressed powder into a mold at 10MPa, crush and sieve after semi-coking treatment to get modified powder A;

[0087] 3) Take 67 parts of graphite waste powder, 33 parts of pitch (including 13 parts of impregnated pitch and 20 parts of modified pitch), put the graphite waste powder into the mixing kettle, knead at 110°C for 1h, the speed is 15r / min, remove the water, then raise the temperature of the mixing kettle to 180°C, put in the molten pitch, close the cover and knead for 1h, the speed is adjusted to 50r / min. After kneading, pour out the paste, cool the material, crush and pass through a 160 mesh sieve to get the pressed powder. After 5h, press the pressed powder into a mold at 10MPa, crush and sieve after semi-coking treatment to get modified powder B;

[0088] 4) Accurately weigh 40 parts of high temperature pitch, take 40 parts of modified powder A and 60 parts of modified powder B; 10 parts of boron nitride and 5 parts of zirconium diboride;

[0089] 5) Mix the modified powder A, modified powder B, 10 parts of boron nitride and 5 parts of zirconium diboride in a mixing machine for 30min, then put them into the mixing kettle, remove the water at 110°C, the speed is 15r / min, then raise the temperature in the kettle to 200°C, put in the high temperature pitch at the corresponding temperature, adjust the speed to 50r / min, close the cover and knead for 1h.

[0090] 6) Quickly put the paste obtained in 5) into a tablet press, the temperature of the tablet press is 200°C, press the tablet 3 times, the thickness of the tablet is 2mm, after pressing, cool the material, stand for 5h, then crush and pass through a 200 mesh sieve; stand for 5h to get the pressed powder;

[0091] 7) Press the pressed powder obtained in 6) into a mold at 1MPa, seal it in a vacuum packaging bag, stand for 2h, then cold isostatic pressing at 140MPa for 30min, gradient pressure relief; take out and stand for 5h to get a green body with a density of 1.62g / cm 3 ;

[0092] 8) Put the green body obtained in 7) into a graphite crucible, fill it with sand, put the crucible into a calcination furnace, introduce argon, follow the program to raise the temperature, calcine at 1000°C for 4h, program cooling to 200°C, then natural cooling, to get a density of 1.70g / cm 3The calcined block.

[0093] 1) The calcined block obtained in 8) was treated in a graphitization furnace at 2500 DEG C for 4 h, and then the temperature was decreased to 200 DEG C in a programmed manner, and then the temperature was decreased to room temperature naturally, to obtain a graphitized block with a density of 1.82 g / cm 3 .

[0094] The related performance parameters of the carbon graphite materials obtained in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0095] Table 1 Related performance parameters of the carbon graphite materials obtained in Examples 1-3 and Comparative Example 1

[0096]

[0097] From the above table, it can be seen that: (1) the carbon graphite material has good compressive strength and compressive strength by simultaneously modifying the surface of the aggregate and the surface of the oxidation inhibitor, so that the oxidation inhibitor and the aggregate surface active layer can be fully combined, the difference between the thermal expansion coefficients of the oxidation inhibitor and the aggregate is reduced, the oxidation inhibitor and the aggregate are synchronized thermal contraction, and the carbon graphite material has good compressive strength and compressive strength.

[0098] (2) Compared with the comparative example, the modified powder C is added in Example 1, Example 2 and Example 3, which improves the bending strength and compressive strength to a certain extent. The modified powder C is introduced into the composite system as a solid phase, which can improve the densification degree and improve the mechanical properties. The modified powder C can react with oxygen before the matrix material to form a glassy substance, and a layer of oxidation-resistant protective film is formed on the surface of the carbon aggregate, which can act as a barrier to oxygen diffusion and a blocking agent for active sites to a certain extent, and improve the oxidation resistance of the material.

[0099] (3) It can be seen from Comparative Example 3 and Comparative Example 2 that the oxidation inhibitor is not modified, the oxidation inhibitor is difficult to mix uniformly with the aggregate, and the agglomerates are easy to appear, so that the mechanical properties and oxidation resistance of the carbon graphite material cannot be improved.

[0100] Finally, it should be pointed out that the above examples of the present application are only examples for illustrating the present application, and are not a limitation on the embodiments of the present application. Based on the above description, other different forms of changes and variations can be made by those skilled in the art. Here, all the embodiments cannot be exhausted. Any obvious changes or variations derived from the technical solutions of the present application still fall within the protection scope of the present application.

Claims

1. A method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines, characterized in that, Specifically, the following steps are included: (1) Coke powder with D50 less than 10μm is put into a kneading pot and kneaded. After removing moisture, the temperature is raised to 160~190℃. Then, molten asphalt A is added and kneaded under a closed lid. After cooling out of the pot, it is crushed, sieved, and molded. Then, it undergoes semi-coking treatment and is crushed and sieved again to obtain modified powder A. The mass ratio of coke powder to asphalt A is 6~7:3~4. (2) Graphite waste powder with D50 less than 10μm is put into a kneading pot and kneaded. After removing the moisture, the temperature is raised to 160~190℃. Then, molten asphalt B is added and kneaded under a closed lid. After cooling out of the pot, it is crushed, sieved, and molded. Then, it undergoes semi-coking treatment and is crushed and sieved again to obtain modified powder B. The mass ratio of graphite waste powder to asphalt B is 6~7:3~4. (3) The oxidation inhibitor is put into a kneading pot and kneaded. After removing the moisture, the temperature is raised to 160~190 ℃. Then, molten asphalt C is added and kneaded under a closed lid. After cooling, the mixture is crushed, sieved, and molded. Then, it undergoes semi-coking treatment and is crushed and sieved again to obtain modified powder C. The mass ratio of oxidation inhibitor to asphalt C is 6~7:3~4. The oxidation inhibitor is one or more of boron nitride, boron carbide, and zirconium diboride. (4) Mix modified powder A, modified powder B and modified powder C in a mixer at a ratio of 35~40:60~65:5~20, remove moisture and heat to 180~210 ℃, then add molten asphalt D and knead under a closed cover, then roll, crush and sieve to obtain pressed powder; the mass ratio of the mixed powder to asphalt D is 105~115:40~43. (5) Press the powder obtained in step (4) into a green block, and then place it in a graphite crucible for calcination to obtain a density of 1.70~1.76 g / cm³. 3 Calcinated blocks; (6) The calcined block obtained in step (5) is treated in a graphitization furnace at 2500~2800 ℃ for 2~6 h, then the temperature is controlled by a program to cool down to 200~300 ℃, and then naturally cooled to room temperature to obtain a density of 1.80~1.87 g / cm³. 3 Carbon graphite materials.

2. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, The coke powder is obtained by coke pretreatment, and the coke is one or more of calcined pitch coke, needle coke, and Shenmu coke.

3. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, In step (2), the graphite waste powder is subjected to a special magnetic separation device to remove magnetic impurities, then subjected to a Raymond mill for initial grinding, and then subjected to an ultra-fine grinding mill for fine grinding.

4. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, Asphalt A in step (1), asphalt B in step (2), asphalt C in step (3), and asphalt D in step (4) are one or two of impregnated asphalt, medium-temperature asphalt, high-temperature asphalt, and modified asphalt.

5. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, In step (4), when mixing and feeding, the mixture is first mixed at 100~110 ℃ for 30~60 min to remove moisture, and then heated to 180~210 ℃. Molten asphalt D is added to the mixing pot, the mixing pot speed is 30~50 r / min, and the pot is closed and mixed for 0.5~1.5 h.

6. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, In step (4), during the rolling process, the mixed paste is quickly fed into the rolling mill and rolled 1 to 3 times. The thickness of the rolled sheet is 1 to 2.5 mm and the rolling temperature is 180 to 200 ℃. After the rolling is completed, the material is cooled according to the procedure and left to stand for 5 hours. Then it is crushed, ground, and passed through a 100 to 400 mesh sieve. After standing for 5 to 10 hours, pressed powder is obtained.

7. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, The semi-coking process in steps (1), (2) and (3) is as follows: the pressed powder obtained in steps (1), (2) and (3) is molded at 5~20 MPa, placed in a box-type resistance furnace, the air in the furnace is replaced with nitrogen, the heating rate is 20℃ / h, the final temperature in the furnace is controlled at 400~600℃, the final temperature is held for 3~6 h, and after cooling with the furnace, it is crushed and sieved to finally obtain the corresponding modified powder.

8. The method for preparing a high-temperature oxidation-resistant carbon graphite material for aero-engines according to claim 1, characterized in that, The specific steps of step (5) are as follows: the powder is molded at 1~3 MPa, sealed in a vacuum packaging bag, left to stand for 2~4 hours, and then subjected to cold isostatic pressing at 140~200 MPa with gradual pressure release; after being taken out and left to stand for 4~6 hours, a density of 1.58~1.63 g / cm³ is obtained. 3 The green body was prepared by first obtaining a green body block; then placing the green body block in a graphite crucible, filling it with sand, placing the crucible in a calcining furnace, introducing argon gas, and calcining it at 900~1200 ℃ for 2~4 h according to a programmed temperature rise, followed by programmed temperature drop to 200~400 ℃ and natural cooling, resulting in a product with a density of 1.70~1.76 g / cm³. 3 The roasted blocks.

9. A high-temperature oxidation-resistant carbon graphite material for aero-engines, characterized in that, The high-temperature antioxidant carbon graphite material for aero-engines was prepared according to any one of claims 1 to 8.

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